A regulator circuit may generally be used in an integrated circuit to regulate voltages received from an external source. The regulator circuit can be used to ensure that circuitry within the integrated circuit receives supply voltages that are within a predetermined range even when the voltages from an external voltage supply deviate from their nominal levels due to factors such as signal noise, temperature variation, etc.
Typical regulator structures include series voltage regulators and analog shunt regulators. However, other types of regulators such as push-pull shunt regulators have also been increasingly used to regulate voltages in integrated circuits. Unlike linear series voltage regulators and analog shunt regulators, push-pull shunt regulators may overcome the problem of large shunt electrical current getting drawn to ground. Generally, push-pull shunt regulators may reduce voltage headroom and may require fewer area intensive compensation capacitors such as those commonly used in analog shunt regulators.
Conventional push-pull shunt regulators often utilize reference voltages generated using bandgap reference circuits to provide reference voltages that are relatively invariant in the presence of signal noise and power supply voltage fluctuations. When the regulated voltage goes above a reference voltage, the push-pull shunt regulator may source or sink the electrical current so that the electrical current returns to its nominal level. If the average regulated voltage is outside a target range of the reference voltage, the push-pull shunt regulator will continue to sink or source the electrical current, respectively, even in the absence of supply voltage noise. This result in undesirable compensation and it may be necessary to manually program the reference voltage of the bandgap reference circuit to avoid such undesirable compensation.
It is within this context that the embodiments described herein arise.